Various types of touch position detection systems are known in the art. Particularly, a touch panel control device which employs a capacitive system using a capacitance is very convenient to use. This is because such a touch panel control device allows a user to perform a direct touch operation with a fingertip on it and perform a touch operation with an easy-to-use stylus pen made of an electrically conductive material.
Generally, a capacitive touch panel device includes: a touch panel body having a structure in which a plurality of drive electrodes intersect with a plurality of detection electrodes in a grade separation manner; and a touch panel controller for controlling the touch panel body.
The touch panel controller, which is connected to the touch panel through a connector, applies a drive signal to the drive electrodes and detects a touch position based on a detection signal detected by a corresponding one of the detection electrodes. Specifically, when an electrically conductive object approaches or contacts the touch panel body, a change in capacitance occurs at the intersection of a corresponding one of the plurality of drive electrodes and a corresponding one of the plurality of detection electrodes. The touch panel controller can detect a touch position by detecting, from the detection signal detected by a corresponding one of the detection electrodes, a signal intensity at a pair of coordinates of the touch panel body, which correspond to the intersection of a corresponding one of the drive electrodes and a corresponding one of the detection electrodes.
The conventional technique relating to a touch panel controller as described above is disclosed in Patent Literature 1. The touch panel controller disclosed in Patent Literature 1 improves the accuracy of detection in a specific area, i.e., a predetermined range which can vary depending on a touch position at which a touch is detected by using a detection signal obtained by a detection circuit, by adjusting a pulse frequency of a drive signal from a drive electrode unit and a sampling frequency representing a change of a signal from a detection electrode unit (hereinafter the “pulse frequency” and the “sampling frequency” are collectively referred to as “scanning frequency”) to be high frequencies in such a specific area.